Our old car has no free updates so your question is not what I try to answer.
I have an old Garmin Nüvi that in August got the 2023 update. Have of course no idea how good or bad the new navigation map from Lexus is, but the 2019 I paid a fortune to get after the 2017 that came with the car was not the least better with regard to one-way streets here where we live; exactly same as the 2017.
Garmin has the correct one-way streets. Lexus software is a disaster. Tried to download and install some free updates from Lexus 2 - 3 years ago and it never did function. It came to my USB stick and started in the car, but after 3 hours it told that connection was lost (the USB stick lost connection?) and so was my patience. Do not remember what kind of update it was, but suppose it is not needed and have not tried since. Like Malcolm say downloading from Lexus is "a recipe for disaster".
Not that we use the Garmin in the car, maps on smartphones are far easier to use and come with free updates very often so they are always correct.